Control system



Feb. 17, 1942.

H. O. MCGI LLIN CONTROL SYSTEM Filed Aug. 10, 1939 RIF] LINE

I INVENTOR HOWARD Q-McGlLLlN ATTORNEY Patented Feb. 17, 1942 2,273,126 CONTROL SYSTEM,

Howard 0. McGillin, Philadelphia, Pa., assignor to The Brown Instrument Company, Philadelphia, Pa., a corporation of Pennsylvania Application August 10, 1939, SerialNo. 289,340 7 Claims. (01. 22-89) The present invention relates to a system of controlling temperatures and more particularly to a system of measuring and controlling the temperature of a body of material as it is being moved from one point to another.

It is an object of the present invention to measure a condition of a body of material as it is being transported and as a result of this measurement to control the application of a condition changing medium theretoi It is a further object of this invention to control the temperature of sand used for the making of moulds as it is being taken from a storage bin to a point of use.

It is still a further object of my invention to control the supply of a material to a conveyor belt in response to the temperature of 'the material passing a given point.

In various foundries it is the practice to empty the sand used in moulds in a storage bin, and convey it from this bin as it is needed to a point Fig. 2 is a diagrammatic view of a control instrument used in the system.

As sand that has been used for moulds is re- 7 moved from the castings it is stored in a bin I of reuse. As the sand may be at a temperature of from anywhere between room temperature to a thousand degrees or so, depending upon how recently it has been used, some means is necessary to bring the temperature down to a point at which the sand may be conveniently handled. On the otherhand if the sand is too cool it has to be reheated before use, so there is an optimum temperature which it is desirable to, maintain. The apparatus of th present invention is designed to measure the temperature of the sand as it is moving past a point and to control the application of a cooling spray thereto in response to its temperature.

standing of the invention, however, its advantages and specific objects obtained with its use, reference should be had to the accompanying drawing and descriptive matter in which I have illustrated and described a preferred embodiment of the invention.

Inthe drawing:

Fig. 1 is a view of the component parts of my control system; and

until such time asit is again needed. This sand is usually at a very high temperature when it is put in the bin and if it is to be used again soon some means has to beprovided to cool it. From the bin I the sand falls on a metal conveyer belt 2 passing over rollers 3 one of which is driven by a motor 4. From the belt 2 the sand -is dropped on a rubber belt 5 and conveyed to the sand first passes under a roller 6 mounted on a support I that is pivoted at 8. Movement of this support 1 controls a switch 9 that, with a 'upon the sand. The arrangement is such' that if no sand is on the belt 2 the roller 6 will be lowered to the position shown to open switch 9 and deenergize the coil II to permit valve I2 to close and stop the flow of the cooling water.

Beyond the roller 6 the sand moves past a thermocoupl I4 that is responsive to its temperature, the thermocouple being connected to a potentiometric measuring and control instrument 15 which is used to adjust the opening of an air operated valve It, also inthe pipe 12.

Beyond the valve IS the pipe I 2 extends into a shielding box-like structure I! and terminates in a spray-head [8 that is adapted to discharge liquid on the sand.

The instrument I5 is preferably an air control potentiometer of the type described in detail in Harrison Patent 2,112,091, issued March 22, 1938. For purposes of illustration herein, however, it is diagrammatically shown in Fig. 2 as comprising an ordinary null-point potentiometric circuit in which the voltage of the thermocouple I4 is im pressed across a portion of a resistor l9 in opposition to the known and constantvoltage of a battery 20. Located in series with the thermocouple is a galvanometer 2| whose pointer 22,.

will deflect in one direction or the other depend 40 which is supplied motor 28 is connected to drive a threaded shaft 2'l to shift a pencarriage 28 along a chart 28 to make a record of the sand temperature. The carriage 28 carriesthe contact 23 to move the 'said contact along the resistance IS in a direction to rebalance the potentiometer circuit and cause pointer 22 to return to its mid-position and open the motor circuit.

Also carried on the pen carriage 28 is a roller 38 which, upon movement of the carriage to some predetermined low position engages the cam edge of a support 3| upon which the switch in is mounted to tilt that support around its pivot 32 against the bias of spring 33 to open that switch andpermit the closing of valve l2. Thus when the sand reaches a predetermined low temperature the supply of cooling fluid in pipe 13 is cut off.

Opening and closing of valve I6 is also accomplished by movement of the pen carriage by means of a cam 34 carried thereby. As the pen carriage moves down scale or to the left for.example, the cam 34 forces a lever 35, pivoted at 35, downwardly so that a pin 31 extending from its lower end recedes from a flapper valve 38.

. This valve 38 is pivoted at 39 and has a natural bias toward the restricted open end of a pipe 'th air at a suitably regulated pressure, past a estriction 4|. A branch 42 of the pipe is connected with a chamber of the valv l6 and above a diaphragm located therein. Therefore as the pen carriage moves down scale the flapper 38 will move nearer to and restrict the leakage through the end of pipe 40. Air pressure will accordingly be built up in that pipe and branch 42 to be applied to the diaphragm of valve It to close the valve. In a similar manner movement of the pen carriage up scale will permit the lever torise under the bias of spring 43 and cause pin 31 to move flapper 38 away from the end of pipe 48. This will permit air to more readily escape therefrom, reducing the pressure on its diaphragm so that the valve I8 may open and supply water to the spray head l8.

If, for some reason, the spray from head l8 was not sufficient to reduce the temperature of the sand below the danger point or if the supply of water thereto was discontinued the belt 5 would be injured or destroyed unless a safety device similar to the one now to be described was provided to prevent hot sand from being dropped upon that belt. In the path of the sand onbelt 2 beyond the shielding structure I1 is located a bulb 44 that is filled with some suitable temperature responsive substance that upon heating thereof will expand and elongate a bellows element 45. This element along with a pivoted switch support 46 and a mercuryswitch 41, is located in a casing 48. When the temperature of the sand passing the bulb 44 is too high the bellows 45 will expand and move support 48 around its pivot toclose the switch 41 which is in a circuit containing a signal 49-and the coil 58 of a switch 5|. Thus when switch 41 is closed the signal 49 will be energized to indicate either audibly or visually or both that the sand temperature is too high and the switch it will be opened against the bias 0"! a spring 58. Opening of the switch 5| deenergizes the drive motor 4 and a coil 53, which through its core member maintains a closure member 54 for the bin I open against its closing tendency that is provided by the spring 55. A switch 58 is provided in the motor line to shut down the system manually when desired.

A general summary of the operation of this system will now be given. Upon closure of the switch 58 which sets motor 4 in operation the belt 2 will start moving to deliver sand to the belt 5. If no sand is going from the bin I the roller 8 will be in engagement with the belt 2 and the switch 8 will be open thus deenergizing coil H and permitting valve l2 to close to shut ofi the supply of water. When sand starts to be carried along the belt 2, the roller 6 will be lifted and switch 9 closed and if the tempera- .ture of the sand is below the danger point switch It will also be closed to energize coil II and open valve I! so that water can be supplied to spray edge 18 as required by the valve it. As the temperature of the sand varies the cam 34 of the instrument l5 will be moved relativeto the lever 35 and thereby move flapper 38 with respect to the restricted end of pipe 48. Such movement will vary the air pressure applied to the diaphragm of valve l6 so that valve will be opened and closed in an amount proportional to the temperature of the sand thus controlling the proper amount of cooling water to be sprayed on r the sand as it is carried beneath the structure II. If for some reason the water sprayed upon the sand should not be suflicient to cool it below the danger point the bulb 44 will be heated and thereby cause expansion-of the bellows 45 to close switch 41. This will cause the signal to be given by 43 indicating that the temperature of the sand is too high and will simultaneously open switch 5| in the circuit of motor 4 to stop the belt 2. At the same time the coil 53 will be deenergized so that spring can move the closure member 54 to cut off the supply of sand to the belt 2.

From the above detailed description it will be seen that I provided a control system whereby the temperature of a material that is being conveyed past a point may be automatically controlled at will. I have also provided a safety device which will prevent damageto any subsequent apparatus with which the material whose temperature is being controlled may come in contact.

While I have described my invention as being used to lower the temperature of sand I do' not wishvto be limited thereto, since it will be obvious from the description that my control sys tem may be used to control the temperature of any material that is being moved past a point and it will also be obvious that some heating me;

dium instead of a cooling medium may be supplied if so desired.

While in accordance with the provisions of the statutes, I have illustrated and described the best form of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of my invention as set forth in the appended claims, and that in some cases certain features of my invention may sometimes be used to advantage without a corresponding use of other features.

Having now described my invention, what 1 claim as new and desire to secure by Letters Patent is:

1. In a system for controlling the temperature of a material, the combination with means to convey the material through a path, means located adjacent said path responsive to passage of said material, a valve operated thereby to control the supply of a temperature changing medium to be applied to said material, separate means in proximity to the material and responsive to its temperature to adjust said valve and therefore saidsupply of temperature changing medium in accordance therewith, and other means also in proximity to said material and responsive to a predetermined temperature thereof to stop the supply of said material on said conveying means.

2. In a system of the class described the com bination with means to convey material to be I said path responsive to the passage of said material, means located along said path responsive to a condition of said material cooperating with said second means to control said mechanism, and other means controlled by said last named means alone to adjust the mechanism and therefore the supply of the condition changing medium in response to a condition of said material.

3. In a control system, means to convey material to be treated from a point of supply through a path, means to control the temperature of said material, means responsive to the tempera ture of said material to regulate said control means and separate means in said path beyond said control means responsive to a predetermined temperature of the material to stop the supply of said material to said control means.

4. In a control system m ans to convey material from a point of supply through a' path, means to regulate a supply of a condition chang ing medium to act on said material as it passes through said path, means adjacent said material and responsive to its passage and means in the a predetermined low temperature thereof to adjust said regulating means and stop the supply of said condition changing medium and means also in the path of said material responsive to a second predetermined temperature thereof to stop the supply of said material on said conveying means.

- 5. In a control system for'controlling the temperature of a material moving from a point of supply through a path, means to regulate a supply of temperature changing medium to be applied thereto, means to continuously measure-the temperature of said material and means responsive ,to the temperature measuring means to control the regulating means and therefore the application of said temperature changing medium to said material, means actuated upon discontinuance of the material to adjust said regulating means to cut off the supply of the temperature changing medium and means responsive to failure of the supply of the temperature changing medium to cut off the supply of material.

, moulds, a storage bin for the sand, means to path of said material as it travels responsive to 6. In apparatus to condition sand for use in moulds, the combination for a bin with a supply of sand, of'means to convey sand from the bin to a point of use, means to regulate a source of temperature changing medium, means responsive to the passage of sand on said conveying means past a point to control said regulating means and therefore the application of said tern-F perature changing medium from said source, and means responsive to the temperature of the sand to adjust the regulating means to adjust the volume of the temperature changing medium applied thereto.

7. In apparatus to condition sand for use in 

